After a couple of hours I now have a working solution in the desginer 309.

There where many issues while upgrading:

I had a view with a custom property called "fullscreen:true" it resultet in the view not being visible in designer. This must be a bug? I need it to be fullscreen.

There where a list that was grouped it also made the whole view invisible in designer (was a child)

A store that was setup for grouped/indexbar gave me a "undefined error" message on startup. I had to delete it and create it again.

The last was kind of funny. There where a lot of models that was not visible from within the designer but there where files in the folders. They where created after renaming some models? Running the application made it complain about referring to files that no longer exists.

Hope it can help? And awesome that I know can commit to SVN without any errors :-)